The present invention relates generally to cabin tent structures, and more particularly to tent pole and hub systems as well as fabric-covered structures
One of the earliest forms of shelter known to humankind is the tent. Huge variety in tent design exists, but common elements include tent fabric and tent poles which shape and support the fabric. Most tents use multiple tent poles, often with hubs connecting the tent poles together. It therefore becomes the combination of poles and hubs which define many characteristics of such tents. Examples of important characteristics include structural shape, rigidity, ability to support the tent fabric, and reaction to externally applied stresses such as those caused by bumping into the tent or from wind buffeting the tent and causing the walls to vibrate.
For purposes of the following discussion, tent poles will be classed as side poles, gable poles, ridge poles, and horizontal poles. In assembled tents, side poles extend in a generally vertical orientation from the ground surface up to the beginning of the roof region of a tent. Gable poles extend from the edge of a tent roof upward to the peak of the tent roof, and have a sloping orientation (i.e., generally in the range of 30 to 60 degrees relative to horizontal). Ridge poles are generally horizontal, but for discussion here are strictly defined as being at the peak of the tent roof (the term tie pole is sometimes used for this). Finally, horizontal poles are herein strictly defined as including all generally horizontally oriented poles except ridge poles (e.g., they include poles typically used at the eaves or lower roof edges of some tent designs).
Balancing tent pole system characteristics is not an easy engineering task. Some of the already mentioned characteristics urge contradictory engineering solutions. For example, strong rigid shapes generally are best accomplished by framing the shape in closed geometric shapes, such as the triangular and rectangular members used in engineering wire-frame drawings. Unfortunately, while framed sections are strong and rigid, they also transmit force and vibration very well, often with undesirable results. Further, framed sections may require more parts than other designs, and therefore may result in increased overall tent weight and cost. Thus, optimizing only some characteristics may conflict with general goals for an entire tent system.
For discussion here, tent pole systems can be defined as free standing, pre-stressed, and gravity assisted systems. In the market today, the free standing system is used primarily for larger tents (including yurts, and show tents); the pre-stressed construction is used primarily in smaller, shorter type (one and two person) portable tents; and gravity assisted systems are primarily used for cabin tents (i.e., tents large enough to accommodate at least a small family, and usually tall enough that an average adult can stand fully upright in the tent center). A good example of a free standing tent system is the teepee. It has a very strong and rigid frame over which fabric is draped. However, the fabric adds nothing to the strength or shape of the finished tepee. When designing tepees the tent fabric and the tent pole system are effectively two unrelated problems. At an opposite extreme are pre-stressed pole systems, good examples of these can be found today in tents using fiberglass poles which are bent into place during assembly and held together by the tent fabric in a spring-like manner to define the tent structure. Attempting to assemble such a tent with only the poles and hubs (if any) would be impossible, or at best produce a very flimsy structure. Finally, in a category falling between the free standing and pre-stressed systems are gravity-assisted systems. Many cabin tents in the market today belong in this classification. In such tents the poles do not form as strong a system as when no tent fabric is assembled onto them, nor are the tent poles intentionally bent in the manner of springs to assemble and tension the tent. Rather, once assembled onto a finished tent, the fabric under the weight of gravity helps to define and stabilize the final tent structure. In such tents the critical components become the hubs used to connect the tent poles, since it is in these that forces concentrate and must be accommodated.
Various forces are applied to tent hubs, either directly, or more commonly indirectly, through the tent poles inserted into the hubs. One such force is fabric weight, which actually may be variable, since rain, snow, and other substances can xe2x80x9cweigh downxe2x80x9d tent fabric. External stresses form another group of forces which also ultimately reach the hubs. Assembled tents may be bumped by users who are either inside or outside of the tent. And when present, wind may range from constantly pressing against the tent from one direction to buffeting it from rapidly changing directions at different speeds, thereby causing vibration in the tent structure. It therefore follows that for a cabin tent design to be acceptable the hubs which are used must successfully deal with all of these forces.
Additional concerns for many tent designs are parts count and overall tent weight. Reducing parts count has the obvious advantage that fewer parts mean less loss or misplacement and almost always reduces cost also, particularly if the eliminated parts are tent poles made of aluminum. And, usually, reducing parts count leads to a more intuitive assembly process, and sometimes a simpler one as well. Further, it may strongly affect tent weight. Generally, of the three major components used in cabin tents the fabric is least dense, the hub has intermediate density (at least in plastic hubs, as are preferred today), and the poles are most dense, since they are metal or high density plastic like fiberglass. There are, of course, also notable size differences in these components. For example, hubs and poles are markedly different in size. Thus, by accepting some size increase in smaller less dense parts, to eliminate some high density large parts entirely, an overall weight savings may be accomplished by selective parts count reduction.
From the above discussion it should be clear that good tent design must balance many factors.
Accordingly, it is an object of the present invention to provide a tent which can be assembled in very little time, and with a minimum of separate pieces.
Another object of the invention is to provide a tent which has a convertible roof.
And, another object of the invention is to provide a tent which has an exterior screen structure.
Briefly, one preferred embodiment of the present invention is an improved tent for quick construction, including a fabric enclosure which serves as walls, roof and floor of the tent. The tent also includes a frame which attaches to and supports the fabric enclosure. The frame includes at least two frame poles having upper and lower ends. The frame poles form at least one V-shape, the lower ends being positioned in close proximity to form the tip of the V-shape, and the upper ends spread apart forming the legs of the V shape. The upper ends tend to fall away from each other on either side of a bisecting vertical line to the extent allowed by their attachment to the fabric enclosure, thereby spreading the fabric enclosure and aiding in the quick construction of the tent.
A second preferred embodiment of the present invention is a convertible tent which includes a fabric enclosure which serves as walls, roof and floor of the tent. A frame supports the fabric enclosure and configures the fabric enclosure into a tent. The tent roof includes a top portion and a screen portion, the top portion being convertible so that the screen portion is exposed.
A third preferred embodiment of the present invention is a tent with an exterior screen structure having an inner tent structure, including an inner fabric enclosure which serve as walls, roof and floor of the inner tent structure and an outer tent structure including an outer fabric enclosure. A single frame supports both inner and outer fabric enclosures.
An advantage of the present invention is that the first preferred embodiment contains a V-shaped side support structure which minimizes the number of pieces required for assembly of the tent.
Another advantage of the invention is that a second preferred embodiment contains a screened roof portion which can be exposed to present a convertible roof.
And, another advantage of the invention is that a third preferred embodiment includes a inner structure which is enclosed by an outer screen structure. The space between the inner and outer structures provides a protected living area for users.
These and other objects and advantages of the present invention will become clear to those skilled in the art in view of the description of the best presently known mode of carrying out the invention and the industrial applicability of the preferred embodiment as described herein and as illustrated in the several figures of the drawings.